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1 |
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2 /* pngwio.c - functions for data output |
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3 * |
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4 * Last changed in libpng 1.2.30 [August 15, 2008] |
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5 * For conditions of distribution and use, see copyright notice in png.h |
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6 * Copyright (c) 1998-2008 Glenn Randers-Pehrson |
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7 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) |
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8 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) |
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9 * |
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10 * This file provides a location for all output. Users who need |
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11 * special handling are expected to write functions that have the same |
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12 * arguments as these and perform similar functions, but that possibly |
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13 * use different output methods. Note that you shouldn't change these |
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14 * functions, but rather write replacement functions and then change |
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15 * them at run time with png_set_write_fn(...). |
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16 */ |
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17 |
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18 #define PNG_INTERNAL |
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19 #include "png.h" |
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20 #ifdef PNG_WRITE_SUPPORTED |
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21 |
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22 /* Write the data to whatever output you are using. The default routine |
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23 writes to a file pointer. Note that this routine sometimes gets called |
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24 with very small lengths, so you should implement some kind of simple |
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25 buffering if you are using unbuffered writes. This should never be asked |
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26 to write more than 64K on a 16 bit machine. */ |
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27 |
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28 void /* PRIVATE */ |
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29 png_write_data(png_structp png_ptr, png_bytep data, png_size_t length) |
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30 { |
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31 if (png_ptr->write_data_fn != NULL ) |
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32 (*(png_ptr->write_data_fn))(png_ptr, data, length); |
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33 else |
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34 png_error(png_ptr, "Call to NULL write function"); |
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35 } |
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36 |
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37 #if !defined(PNG_NO_STDIO) |
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38 /* This is the function that does the actual writing of data. If you are |
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39 not writing to a standard C stream, you should create a replacement |
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40 write_data function and use it at run time with png_set_write_fn(), rather |
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41 than changing the library. */ |
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42 #ifndef USE_FAR_KEYWORD |
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43 void PNGAPI |
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44 png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length) |
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45 { |
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46 png_uint_32 check; |
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47 |
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48 if (png_ptr == NULL) return; |
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49 #if defined(_WIN32_WCE) |
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50 if ( !WriteFile((HANDLE)(png_ptr->io_ptr), data, length, &check, NULL) ) |
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51 check = 0; |
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52 #else |
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53 check = fwrite(data, 1, length, (png_FILE_p)(png_ptr->io_ptr)); |
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54 #endif |
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55 if (check != length) |
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56 png_error(png_ptr, "Write Error"); |
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57 } |
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58 #else |
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59 /* this is the model-independent version. Since the standard I/O library |
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60 can't handle far buffers in the medium and small models, we have to copy |
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61 the data. |
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62 */ |
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63 |
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64 #define NEAR_BUF_SIZE 1024 |
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65 #define MIN(a,b) (a <= b ? a : b) |
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66 |
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67 void PNGAPI |
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68 png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length) |
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69 { |
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70 png_uint_32 check; |
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71 png_byte *near_data; /* Needs to be "png_byte *" instead of "png_bytep" */ |
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72 png_FILE_p io_ptr; |
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73 |
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74 if (png_ptr == NULL) return; |
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75 /* Check if data really is near. If so, use usual code. */ |
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76 near_data = (png_byte *)CVT_PTR_NOCHECK(data); |
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77 io_ptr = (png_FILE_p)CVT_PTR(png_ptr->io_ptr); |
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78 if ((png_bytep)near_data == data) |
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79 { |
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80 #if defined(_WIN32_WCE) |
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81 if ( !WriteFile(io_ptr, near_data, length, &check, NULL) ) |
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82 check = 0; |
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83 #else |
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84 check = fwrite(near_data, 1, length, io_ptr); |
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85 #endif |
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86 } |
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87 else |
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88 { |
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89 png_byte buf[NEAR_BUF_SIZE]; |
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90 png_size_t written, remaining, err; |
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91 check = 0; |
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92 remaining = length; |
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93 do |
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94 { |
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95 written = MIN(NEAR_BUF_SIZE, remaining); |
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96 png_memcpy(buf, data, written); /* copy far buffer to near buffer */ |
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97 #if defined(_WIN32_WCE) |
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98 if ( !WriteFile(io_ptr, buf, written, &err, NULL) ) |
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99 err = 0; |
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100 #else |
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101 err = fwrite(buf, 1, written, io_ptr); |
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102 #endif |
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103 if (err != written) |
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104 break; |
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105 else |
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106 check += err; |
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107 data += written; |
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108 remaining -= written; |
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109 } |
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110 while (remaining != 0); |
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111 } |
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112 if (check != length) |
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113 png_error(png_ptr, "Write Error"); |
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114 } |
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115 |
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116 #endif |
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117 #endif |
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118 |
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119 /* This function is called to output any data pending writing (normally |
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120 to disk). After png_flush is called, there should be no data pending |
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121 writing in any buffers. */ |
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122 #if defined(PNG_WRITE_FLUSH_SUPPORTED) |
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123 void /* PRIVATE */ |
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124 png_flush(png_structp png_ptr) |
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125 { |
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126 if (png_ptr->output_flush_fn != NULL) |
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127 (*(png_ptr->output_flush_fn))(png_ptr); |
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128 } |
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129 |
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130 #if !defined(PNG_NO_STDIO) |
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131 void PNGAPI |
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132 png_default_flush(png_structp png_ptr) |
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133 { |
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134 #if !defined(_WIN32_WCE) |
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135 png_FILE_p io_ptr; |
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136 #endif |
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137 if (png_ptr == NULL) return; |
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138 #if !defined(_WIN32_WCE) |
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139 io_ptr = (png_FILE_p)CVT_PTR((png_ptr->io_ptr)); |
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140 if (io_ptr != NULL) |
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141 fflush(io_ptr); |
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142 #endif |
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143 } |
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144 #endif |
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145 #endif |
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146 |
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147 /* This function allows the application to supply new output functions for |
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148 libpng if standard C streams aren't being used. |
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149 |
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150 This function takes as its arguments: |
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151 png_ptr - pointer to a png output data structure |
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152 io_ptr - pointer to user supplied structure containing info about |
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153 the output functions. May be NULL. |
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154 write_data_fn - pointer to a new output function that takes as its |
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155 arguments a pointer to a png_struct, a pointer to |
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156 data to be written, and a 32-bit unsigned int that is |
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157 the number of bytes to be written. The new write |
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158 function should call png_error(png_ptr, "Error msg") |
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159 to exit and output any fatal error messages. |
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160 flush_data_fn - pointer to a new flush function that takes as its |
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161 arguments a pointer to a png_struct. After a call to |
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162 the flush function, there should be no data in any buffers |
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163 or pending transmission. If the output method doesn't do |
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164 any buffering of ouput, a function prototype must still be |
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165 supplied although it doesn't have to do anything. If |
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166 PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile |
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167 time, output_flush_fn will be ignored, although it must be |
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168 supplied for compatibility. */ |
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169 void PNGAPI |
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170 png_set_write_fn(png_structp png_ptr, png_voidp io_ptr, |
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171 png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn) |
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172 { |
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173 if (png_ptr == NULL) return; |
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174 png_ptr->io_ptr = io_ptr; |
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175 |
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176 #if !defined(PNG_NO_STDIO) |
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177 if (write_data_fn != NULL) |
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178 png_ptr->write_data_fn = write_data_fn; |
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179 else |
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180 png_ptr->write_data_fn = png_default_write_data; |
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181 #else |
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182 png_ptr->write_data_fn = write_data_fn; |
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183 #endif |
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184 |
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185 #if defined(PNG_WRITE_FLUSH_SUPPORTED) |
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186 #if !defined(PNG_NO_STDIO) |
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187 if (output_flush_fn != NULL) |
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188 png_ptr->output_flush_fn = output_flush_fn; |
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189 else |
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190 png_ptr->output_flush_fn = png_default_flush; |
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191 #else |
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192 png_ptr->output_flush_fn = output_flush_fn; |
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193 #endif |
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194 #endif /* PNG_WRITE_FLUSH_SUPPORTED */ |
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195 |
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196 /* It is an error to read while writing a png file */ |
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197 if (png_ptr->read_data_fn != NULL) |
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198 { |
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199 png_ptr->read_data_fn = NULL; |
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200 png_warning(png_ptr, |
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201 "Attempted to set both read_data_fn and write_data_fn in"); |
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202 png_warning(png_ptr, |
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203 "the same structure. Resetting read_data_fn to NULL."); |
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204 } |
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205 } |
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206 |
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207 #if defined(USE_FAR_KEYWORD) |
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208 #if defined(_MSC_VER) |
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209 void *png_far_to_near(png_structp png_ptr, png_voidp ptr, int check) |
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210 { |
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211 void *near_ptr; |
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212 void FAR *far_ptr; |
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213 FP_OFF(near_ptr) = FP_OFF(ptr); |
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214 far_ptr = (void FAR *)near_ptr; |
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215 if (check != 0) |
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216 if (FP_SEG(ptr) != FP_SEG(far_ptr)) |
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217 png_error(png_ptr, "segment lost in conversion"); |
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218 return(near_ptr); |
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219 } |
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220 # else |
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221 void *png_far_to_near(png_structp png_ptr, png_voidp ptr, int check) |
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222 { |
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223 void *near_ptr; |
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224 void FAR *far_ptr; |
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225 near_ptr = (void FAR *)ptr; |
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226 far_ptr = (void FAR *)near_ptr; |
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227 if (check != 0) |
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228 if (far_ptr != ptr) |
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229 png_error(png_ptr, "segment lost in conversion"); |
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230 return(near_ptr); |
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231 } |
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232 # endif |
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233 # endif |
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234 #endif /* PNG_WRITE_SUPPORTED */ |